The present invention relates to a display device comprising:                a matrix of rows and columns of pixels,        a group of first wires, each first wire coupled to a respective one of the rows of pixels,        a group of second wires, each second wire coupled to a respective one of the columns of pixels,        first voltage applying means for applying a scanning voltage to each of the first wires successively and        second voltage applying means for applying respective signal voltages to each of the second wires in synchronization with the scanning voltage successively applied to the first wires.        
In recent years, electronic devices equipped with flat panel displays such as a liquid crystal display (hereinafter referred to as “LCD”), a plasma display panel (PDP), a field emission display (FED) and an organic EL (electroluminescence) display as display devices are becoming widespread rapidly. Above all, the widespread use of electronic devices equipped with LCDs is remarkable and they cover a fairly broad spectrum of applications.
Examples of LCDs include so-called active matrix type LCDs using thin film transistors hereinafter referred to as “TFTs”. These TFTs make it possible to implement an LCD provided with multiple scanning lines as, for example, required for large screen or high definition displays, with excellent display performance such as contrast and on/off response. Such an active matrix type LCD generally comprises an array of pixels arranged in a matrix of horizontal and vertical lines. Horizontal lines are also called scanning lines or rows; vertical lines are also called signal lines or columns. Driving circuits are provided for both the horizontal and vertical lines, and each pixel is provided with a TFT as a switching element. In this LCD, the horizontal driving circuit cyclically supplies a sequential scanning voltage to the scanning lines for driving TFTs line by line in sequence, while the vertical driving circuit, operating in synchronization with the horizontal driving circuit, selectively supplies signal voltages to the signal lines according to an image signal. In this way, pixels are selected through the scanning lines one row of pixels at a time from top to bottom. Signal voltages are applied to each of the respective electrodes of the pixels on the selected scanning line via the corresponding signal lines in a sequential manner. The signal voltages are written at the respective electrodes of the pixels and an image is displayed on the display panel. Thus, within a period during which one scanning line is selected, hereinafter also referred to as “horizontal scanning period”, the signal voltages are supplied to the pixels corresponding to the scanning line.
However, since the signal lines are normally made of a conductive material, the above-mentioned conventional LCD has a problem that a time constant of the signal line affects the display performance of the LCD. This often becomes problematic especially in such a case as a large display and a high definition display.
FIG. 4 is a timing chart when a voltage is applied to each pixel of the conventional LCD. FIGS. 4A to 4E illustrate signals on the scanning lines of the first to third rows R1, R2, R3, the (M-1)th row RM-1 and the Mth row RM and FIG. 4F illustrates a signal, indicated by NES, of an arbitrary signal line close to the horizontal driving circuit and FIG. 4G illustrates a signal, indicated by FES, of a signal line remote from the horizontal driving circuit. As shown in FIGS. 4A to 4E, the horizontal scanning period t is the time period allocated to each line for scanning this line. During a vertical scanning period T the selection of all scanning lines is completed once. For this reason, if the time constant increases, the signal voltages, while writing pixels on the nearer end side NES close to the vertical driving circuit, reach still the target potential TP during the horizontal scanning period t as shown in FIG. 4F, whereas for pixels on the farther end side FES remote from the vertical driving circuit, the waveforms of the signal voltages applied to the signal lines become less steep and the signal voltages do not reach the target potential TP within the horizontal scanning period t, making it difficult to write correct signal voltages to the pixels. This would lead to deterioration of the display performance of the device such as brightness deviations.
A possible way to solve this problem is to lengthen each horizontal scanning period t. However, simply lengthening each horizontal scanning period t means lengthening the vertical scanning period T, which would lead to deterioration of display quality due to flickering.